Technical Abstract:
Oxygen-derived free radicals have been implicated in the pathophysiology of several human diseases. Definitive evidence is lacking, in part, because of inadequate methodologies to assess oxidative status in humans in vivo. We developed an assay system for 8-iso-prostaglandin F2alpha, a product of free radical-catalyzed peroxidation of arachidonic acid, and a putative marker of oxidative stress. The procedure involves solid phase extraction HPLC and TLC. Quantification was achieved by capillary GC-ECCI-mass spectrometry with a tetradeuterated analog as internal standard. The interassay coefficient of variation in two separate determinations was 1.6% (n=4) and 2.3% (n=4). The validity of the assay was assessed through recovery experiments. The equation of the regression plot correlating the amounts added and recovered was y=0.91x-0.31 with r=0.9916 (n=12). The minimum amount of analyte that we could measure accurately was 25 pg/ml of urine. The pair of fragment ions ([M-181]) at m/z 569 and m/z 573 were monitored for quantification. Intake of 80 mg/d of lycopene by eleven volunteers for four weeks resulted in a non-significant reduction of 8-iso- PGF2alpha excretion.